Several categories of lighting fixtures exist for warehouse/factory-type applications, including: high bay and low bay. Industrial buildings and workplaces require lighting systems that provide appropriate quantities of energy-efficient lighting. High bay (sometimes referred to as “hibay”) applications typically have a mounting height between 20 and 40 feet above the floor and the fixtures are individually mounted as “point sources.” Low bay applications typically have a mounting height less than 20 feet above the floor and the fixtures are mounted in close proximity to each other, and in some cases the fixtures may even touch one another. High bay fixtures typically have their own power sources, while low bay fixtures typically have power supplied to multiple fixtures in a row through a daisy chain.
High bay spaces are typically found in warehouses, factories, large retail stores, and athletic facilities. High-intensity Discharge (HID) light sources, such as metal halide and high-pressure sodium lamps, have long dominated the market for lighting indoor spaces with high ceilings (high bay). HID lamps are typically installed in fixtures that direct their light using parabolic reflectors, which gives them the ability to concentrate light on horizontal work surfaces from lofty mounting heights. However, HID fixtures have negative mercury disposal issues and they are considered “point sources” because they produce intense light in such a small area. For years, fluorescent lamps have been used in low bay applications. Fluorescent lamps emit diffuse light from long glass tubes. This characteristic of diffusivity has enabled fluorescent fixtures to dominate the market for lighting low bay applications. Recently, more intense and efficient fluorescent lamps have been developed (called High-intensity Fluorescent (HIF) lamps), which have enabled fluorescent systems to break through the ceiling-height barrier to compete directly with HID fixtures in the high bay market.
High bay applications tend to have environments that are relatively more harsh and corrosive than low bay applications. In particular, high bay environments can have more airborne dust and oil particulates. Unlike HID lamps, which typically have male-threaded electrodes that screw into female-threaded sockets, fluorescent lamps have exposed pin-type electrodes at the ends of the tubes. Current fluorescent high bay lighting products in the marketplace are designed to use twist-lock or roto-lock style sockets with no protective metal enclosure around the sockets. These types of sockets can cause failure of the fluorescent lamp or fixture when exposed to harsh industrial environments, such as those that expose the fluorescent light fixture and its sockets to oils and solvents.